1. Field of the Invention
The present invention relates to a post-processing liquid application device, an image forming system including a post-processing liquid application device, and a post-processing liquid application method.
2. Description of the Related Art
Techniques are known for applying a post-processing liquid (protector coating liquid) on a print medium after printing an object on the print medium using KCMY ink in order to improve fixation (abrasion resistance) of the printed object. Also, apparatuses are known for applying the post-processing liquid uniformly over the entire surface of a page regardless of the coverage rate representing the ratio of the area of a page portion covered with ink to the total area of the page (see, e.g., Japanese Unexamined Patent Publication No. 2007-055257).
However, the amount of post-processing liquid applied is desirably reduced in order to reduce the cost per page (CPP) and promote rapid drying. In this respect, techniques are known for partially applying the post-processing liquid on a printed portion of a print medium (e.g., portion to which ink is attached to form a character or an image) without considering the coverage rate. In such techniques, the amount of post-processing liquid to be applied may be determined based on the image forming speed (see, e.g., Japanese Unexamined Patent Publication No. 2014-176997).
Note that in the case of partially applying the post-processing liquid only on a printed portion of a print medium, the friction coefficient of a portion of the print medium upon being rubbed against another print medium is higher when the portion does not have the post-processing liquid applied thereon as compared with the friction coefficient when portions both having the post-processing liquid applied thereon rub against one another. Thus, the abrasion resistance of the printed portion may be degraded. Accordingly, in order to maintain an abrasion resistance equivalent to that achieved when full-page application of the post-processing liquid is implemented, the amount of post-processing liquid applied per unit area has to be increased at the portion where the post-processing liquid is applied.